1. Field of the Invention
This invention relates to a novel vehicle headlamp. More specifically, the invention relates to an assembly and technique for securing safety during an operation, such as a discharge bulb-exchanging operation, in a vehicle headlamp having a discharge bulb serving as a light source.
2. Description of the Related Art
For lighting a discharge bulb, it is necessary to apply a high voltage thereto, and therefore a lighting circuit is required to increase a battery voltage, and also to convert it into an alternating (AC) voltage, and apply it to the discharge bulb. Therefore, a vehicle headlamp, having a discharge bulb serving as a light source, is provided with such a lighting circuit.
In order to effect an operation such as a discharge bulb-exchanging operation, a socket, connecting the lighting circuit to the discharge bulb, is removed from the discharge bulb. If this operation is carried out wherein the provision of a lighting switch is omitted, or the operator has forgotten to turn off the lighting switch, a dangerous condition occurs since a high voltage is applied to a terminal portion of the socket.
Therefore, there has been proposed a vehicle headlamp of the type in which a lighting circuit is provided integrally on a cover which can close and open an opening formed in a lamp body (supporting a reflector on which a discharge bulb is mounted) for the purpose of effecting an operation such as a discharge bulb-exchanging operation. An output end of the lighting circuit is connected via a wire harness to a socket which can be releasably attached to the discharge bulb, and an input connector is provided at the lighting circuit, and a power source-side connector, provided at a wire harness extending from a power source portion, is connected to the input connector.
In the above conventional vehicle headlamp, for example, when exchanging the discharge bulb with a new one, the cover is removed from the opening, and also the power source-side connector is disconnected from the input connector. By doing so, the supply of electric power from the power source to the lighting circuit is interrupted, so that the high voltage is not supplied to the terminal portion of the socket, and therefore this is safe. Even if the operator should touch a terminal portion of the power source-side connector, this is not so dangerous since only a battery voltage is applied to this terminal portion.
In the above conventional vehicle headlamp, the power source-side connector is provided at the free end of the wire harness, and therefore the operation, such as the discharge bulb-exchanging operation, can be carried out by moving the cover from the opening without the need for removing the power source-side connector from the input connector.
In the case where there is provided a lighting switch, it is quite possible that a lazy operator, who tends to effect the discharge bulb-exchanging operation without turning off the lighting switch, carries out the discharge bulb-exchanging operation without canceling the connection between the power source-side connector and the input connector.
The invention provides a construction in which an operation, such as a discharge bulb-exchanging operation, can not be carried out unless the supply of electric power to a lighting circuit is completely interrupted, thereby positively ensuring safety during the operation such as the discharge bulb-exchanging operation.
The above problems have been solved by a vehicle headlamp of the invention. A power source-side connector, which is provided on an input line for inputting electric power from a power source into a lighting circuit, and a bulb-side connector, which is connected to one end of an output line which is connected at the other end thereof to a socket so as to output the electric power from the lighting circuit to a discharge bulb, are fixedly secured to that portion of a lamp body disposed in the vicinity of an opening portion. The lighting circuit, which is provided with an input connector for connection to the power sourceside connector, and an output connector for connection to the bulb-side connector, is integrally formed on a cover. When the cover is-moved to open the opening portion, the connection between the power source-side connector and the input connector and the connection between the bulb-side connector and the output connector are simultaneously interrupted.
Therefore, in the vehicle headlamp of the present invention, when the opening portion in the lamp body is opened so as to enable an operation, such as a discharge bulb-exchanging operation, to be effected, the connection between the power source-side connector and the input connector and the connection between the bulb-side connector and the output connector are simultaneously interrupted without fail. Consequently, the electric power will not be supplied to the lighting circuit. Therefore, when the operation, such as the discharge bulb-exchanging operation, is carried out even in a condition in which the operator has forgotten to turn off a lighting switch, the operator will not touch any high voltage-applied portion such as the socket.